1. Field of the Invention
The present invention relates to a technology for recycling rigid polyurethane foam. More specifically, the present invention relates to a technology to decompose rigid polyurethane foam to recycle it as a material of an insulator of a refrigerator or the like.
2. Description of the Related Art
From a viewpoint of resource conservation, recycling of scrapped household electric appliances such as refrigerators and televisions has been emphasized, and various endeavors have been undertaken for that purpose. In recycling of refrigerators, metallic materials such as iron plates and copper pipes can be recycled with relative ease. However, plastics, especially rigid polyurethane foam as a thermosetting resin, which is commonly used for insulators, is difficult to melt and recycle. Generally, such plastics are disposed of in reclaimed lands or incinerated, or they are reused as fillers.
Under this condition, techniques to decompose polymer materials by treating with supercritical water and sub-critical water have been proposed. For example, JP-A-10-310663 suggests a method for decomposing and recycling polyurethane resin. The reference describes decomposition of polyurethane resin by using supercritical or sub-critical water in order to recover starting compounds of the polyurethane resin or available starting derivatives. Japanese Patent No. 2885673 describes decomposing polymer materials by using supercritical or sub-critical water in order to decompose the materials into oils.
However, since rigid polyurethane foam included in a scrapped refrigerator is covered with an iron plate or with an ABS resin, it cannot be decomposed by treating with supercritical water. Various polymer materials used for interior members of a refrigerator, such as polypropylene resin, can be decomposed by using supercritical water or sub-critical water. However, when the members are decomposed together, various resulting low molecular weight materials will be melted as impurities in the mixed materials. As a result, the material cannot be reused for a rigid polyurethane foam material.
Therefore, for the purpose of industrial recycling, discrimination of rigid polyurethane foam from scrapped refrigerators is the most important to recycle starting compounds of polyurethane resin or any available starting derivatives. The rigid polyurethane foam is requested to be free of dissimilar materials or impurities. Another fundamental aim is to establish waste treatment for decomposing and recycling iron and non-ferrous metals and providing a high recycling rate as an entire system.
The chemical structure of rigid polyurethane foam to be decomposed affects the determination on starting compounds of polyurethane resin obtainable by decomposition and available starting derivatives. The factors vary depending on the materials of the original rigid polyurethane foam. Therefore, it is important to select a method of manufacturing materials suitable for the original rigid polyurethane foam.
Still another aim for recycling is to use polyurethane resin compounds obtainable by decomposition and available derivatives, and reuse the materials for insulators of refrigerators.
A critical problem is that when rigid polyurethane foam used in a scrapped refrigerator is not identified properly, suitable methods for treating and manufacturing cannot be determined, and this prevents recycling.
In order to solve the problem described above, the present invention provides a method of manufacturing a raw material of rigid polyurethane foam, a method of manufacturing a refrigerator from recycled rigid polyurethane foam, and a refrigerator, so that the recycling rate for scrapped refrigerators is improved, and thus, the present invention serves for resource conservation.
The method includes steps of shredding a scrapped refrigerator containing rigid polyurethane foam in order to obtain rigid polyurethane foam lumps, grinding the lumps in order to obtain a rigid polyurethane foam powder, liquefying the rigid polyurethane foam powder by either an aminolysis or glycolysis reaction, and reacting the thus obtained liquefied rigid polyurethane foam powder with a supercritical water or sub-critical water in order to decompose the rigid polyurethane foam.
Accordingly, rigid polyurethane foam free of impurities such as resins can be extracted on an industrial scale from a rigid polyurethane foam lump contained in a scrapped refrigerator. It should be specifically noted that since the rigid polyurethane foam is liquefied, fragments of impurities such as other polypropylene resins can be filtered to obtain a pure composition of hard polyurethane foam. By treating the liquefied rigid polyurethane foam powder with supercritical or sub-critical water, the composition can be decomposed into amines and polyol of rigid polyurethane foam having substantially no impurities.
Preferably in the above method, the rigid polyurethane foam powder is liquefied by mixing with an additive comprising at least one compound selected from ethylene glycol, propylene glycol, monoethanolamine and tolylenediamine before heating. Since the compound serves to decompose and liquefy a part of the urethane bonding selectively, fragments of impurities can be removed efficiently.
Preferably in the above method, a ratio of the additive to the rigid polyurethane foam powder is from 0.4:1 to 5.0:1 by weight, and the reaction temperature ranges from 100 to 250xc2x0 C.
Preferably in the above method, a ratio of the supercritical/sub-critical water to the liquefied rigid polyurethane foam powder is from 0.4:1 to 5.0:1 by weight, and the liquefied rigid polyurethane foam powder is reacted with the supercritical/sub-critical water at a temperature ranging from 190 to 400xc2x0 C. and at a pressure ranging from 10 to 25 MPa.
Preferably in the above method, an average particle diameter of the rigid polyurethane foam powder ranges 1 xcexcm to 3 mm.
Preferably in the method, the rigid polyurethane foam is manufactured by foaming either a diphenylmethane diisocyanate composition or a tolylene diisocyanate composition.
A method of manufacturing rigid polyurethane foam according to the present invention comprises steps of:
shredding a scrapped refrigerator including rigid polyurethane foam in order to separate lumps of rigid polyurethane foam,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by an aminolysis reaction or a glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or sub-critical water in order to decompose the rigid polyurethane foam powder to obtain a crude material,
fractionating the crude material, and subsequently addition-polymerizing the fractionated ingredient with at least one of ethylene oxide and propylene oxide in order to synthesize polyetherpolyol.
A method of manufacturing rigid polyurethane foam according to the present invention comprises steps of:
shredding a scrapped refrigerator including rigid polyurethane foam in order to separate lumps of rigid polyurethane foam,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by an aminolysis reaction or a glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or sub-critical water in order to decompose the rigid polyurethane foam powder to obtain a crude material, and
fractionating the crude material and subsequently synthesizing isocyanate by using the fractionated ingredient as a starting material.
It is preferable in the present invention that the crude material is obtained by decomposing rigid polyurethane foam made from a tolylene diisocyanate composition.
Accordingly, the tolylene diisocyanate-based rigid polyurethane foam used for a refrigerator insulator can be recycled easily on an industrial scale. Particularly, tolylenediamine-based polyetherpolyol can be synthesized from tolylenediamine as one of the fractionated ingredients after fractionating crude materials obtained by treatment with supercritical water or sub-critical water. Moreover, tolylene diisocyanate can be synthesized from the tolylene diamine. Materials for manufacturing rigid polyurethane foam can be recycled from scrapped refrigerators in this manner.
A method of manufacturing materials of the rigid polyurethane foam includes steps of:
shredding a scrapped refrigerator comprising rigid polyurethane foam in order to separate rigid polyurethane foam lumps,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by using either aminolysis reaction or glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or a sub-critical water in order to decompose the rigid polyurethane foam into a crude material, and
synthesizing polyetherpolyol by addition polymerization between the crude material and ethylene oxide and/or propylene oxide.
Preferably in the present invention, the crude material is obtained by decomposing rigid polyurethane foam made from a diphenylmethane diisocyanate composition.
Accordingly, rigid polyurethane foam made from a composition of diphenylmethane diisocyanate, which is used for an insulator of a refrigerator, can be recycled on an industrial scale. More specifically, the present invention enables the synthesis of the polyol from an amine initiator obtained by a treatment with supercritical water or sub-critical water. This serves to recycle rigid polyurethane foam materials.
In the present invention, a method of manufacturing a refrigerator includes steps of:
shredding a scrapped refrigerator comprising rigid polyurethane foam in order to separate rigid polyurethane foam lumps,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by using either aminolysis reaction or glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or a sub-critical water in order to decompose the rigid polyurethane foam into a crude material,
fractionating the crude material into a fractionated ingredient and a residue,
mixing isocyanate prepared from the fractionated ingredient as an initiator, the residue, a surfactant agent, a catalyst and a foaming agent,
injecting the mixture in a gap between an inner liner and an outer case of a refrigerator, and
foaming and curing the mixture.
Preferably in the method, the rigid polyurethane foam is made from a tolylene diisocyanate composition.
Accordingly, materials obtained by decomposing and synthesizing rigid polyurethane foam can be reused, and thus, a refrigerator containing such rigid polyurethane foam can be recycled several times in order to serve for resource conservation.
In the present invention, a refrigerator is manufactured by mixing polyetherpolyol, a surfactant agent, a catalyst, a foaming agent and isocyanate, injecting the mixture in a gap between an inner liner and an outer case of the refrigerator and foaming-curing the mixture therein. The polyetherpolyol contains an ingredient of polyetherpolyol prepared by the following steps of:
shredding a scrapped refrigerator comprising rigid polyurethane foam in order to separate rigid polyurethane foam lumps,
grinding the rigid polyurethane foam lumps into a rigid polyurethane foam powder,
liquefying the rigid polyurethane foam powder by using either aminolysis reaction or glycolysis reaction,
reacting the liquefied rigid polyurethane foam powder with either supercritical water or a sub-critical water in order to decompose the rigid polyurethane foam into a crude material, and
subjecting the crude material to addition polymerization with ethylene oxide and/or propylene oxide.
Preferably, the rigid polyurethane foam is made from a composition of diphenylmethane diisocyanate.
In this way, polyetherpolyol can be obtained from rigid polyurethane foam made from a diphenylmethane diisocyanate composition used as a refrigerator insulator, and the polyetherpolyol can be reused as a material for rigid polyurethane foam. The thus obtained refrigerator serves for resource conservation and it is environmentally-friendly. Needless to say, such refrigerators can be recycled.
Furthermore, a refrigerator in the present invention is manufactured by filling rigid polyurethane foam, and the refrigerator is provided with a means such as a label to identify materials of the rigid polyurethane foam used as an insulator.
In the present invention, materials of rigid polyurethane foam contained in a scrapped refrigerator can be discriminated. Therefore, the materials can be separated from a scrapped refrigerator and recycled easily since it is possible to determine suitable methods for treating and manufacturing materials.
Preferably, the rigid polyurethane foam to be discriminated is manufactured by foaming a material containing at least one composition selected from a tolylene diisocyanate composition, a diphenylmethane diisocyanate composition, and a mixture thereof, and the material is identified on the color tones.
Accordingly, the material composition of rigid polyurethane foam contained in a scrapped refrigerator can be identified based on the color tones whether it is a tolylene diisocyanate composition, a diphenylmethane diisocyanate composition, or a mixture thereof. As a result, suitable methods for treating and manufacturing raw materials can be determined and recycling procedures can be simplified. In addition, this serves to prevent errors in treatment and manufacturing operations.
Preferably, a means for identifying materials is displayed or recorded on a seal cap covering an injection hole. Such a hole is formed on the outer case or on the backside of the refrigerator in order to inject a raw material of polyurethane.
Accordingly, recycling operations can be performed suitably and efficiently for every urethane material in recycling facilities. The identifying means will help operators to determine treatment of the rigid polyurethane foam.
A refrigerator according to the present invention contains an insulator of polyurethane foam manufactured from a material containing an ingredient prepared by any of the above-mentioned methods.
The present invention provides a resource-conservative refrigerator, since the rigid polyurethane foam material is obtained from a tolylene diisocyanate composition or a diphenylmethane diisocyanate composition as products of decomposition and synthesis of rigid polyurethane foam used for a refrigerator insulator. Due to the identifying means, the rigid polyurethane foam insulator contained in a scrapped refrigerator can be recycled easily.
Since polyetherpolyol obtained by re-synthesizing is reused for a rigid polyurethane foam material, the present invention can provide refrigerators serving for resource conservation. Moreover, the rigid polyurethane foam insulator contained in a scrapped refrigerator can be recycled due to the identification ability.
As mentioned above, the present invention provides a method of treating waste, and the method includes:
a stage of shredding waste such as a refrigerator comprising rigid polyurethane foam,
a stage of sorting the shredded waste into iron, non-ferrous metals, rubbers or the like,
a stage of treating foamed insulator, and this stage includes a step of pulverizing rigid polyurethane foam lumps by using grinding means or compressing means;
a stage of recycling, and this stage includes liquefying the rigid polyurethane foam powder by using aminolysis reaction or glycolysis reaction, filtering the liquefied rigid polyurethane foam powder to remove impurities such as resin fragments and metallic fragments and subsequently decomposing the material of the rigid polyurethane foam into amines and starting compound of rigid polyurethane foam by using reaction with supercritical water or sub-critical water.